Homogeneous porous low dielectric constant materials

ABSTRACT

In one exemplary embodiment, a method includes: providing a structure having a first layer overlying a substrate, where the first layer includes a dielectric material having a plurality of pores; applying a filling material to an exposed surface of the first layer; heating the structure to a first temperature to enable the filling material to homogeneously fill the plurality of pores; after filling the plurality of pores, performing at least one process on the structure; and after performing the at least one process, removing the filling material from the plurality of pores by heating the structure to a second temperature to decompose the filling material.

CROSS-REFERENCE TO RELATED APPLICATIONS

This patent application claims priority under 35 U.S.C. §119(e) fromU.S. Provisional Patent Application No. 61/298,696, filed Jan. 27, 2010,the disclosure of which is incorporated by reference herein in itsentirety.

TECHNICAL FIELD

The exemplary embodiments of this invention relate generally tosemiconductor devices and, more specifically, relate to porousdielectric materials.

BACKGROUND

This section endeavors to supply a context or background for the variousexemplary embodiments of the invention as recited in the claims. Thecontent herein may comprise subject matter that could be utilized, butnot necessarily matter that has been previously utilized, described orconsidered. Unless indicated otherwise, the content described herein isnot considered prior art, and should not be considered as admitted priorart by inclusion in this section.

It is widely known that the speed of propagation of interconnect signalsis one of the most important factors controlling overall circuit speedas feature sizes are reduced and the number of devices per unit areaincreases. Throughout the semiconductor industry, there is a strongdrive to reduce the dielectric constant (k) of the interlayer dielectric(ILD) materials such as those existing between metal lines, for example.As a result of such reduction, interconnect signals travel fasterthrough conductors due to a concomitant reduction inresistance-capacitance (RC) delays.

Porous ultra low-k (ULK) dielectrics have enabled capacitance reductionin advanced silicon complementary metal-oxide semiconductor (CMOS) backend of line (BEOL) structures. However, the high level of porosityrequired (e.g., to achieve k values of 2.4 and lower) create issue interms of dielectric material damage or loss due to plasma exposures(e.g., reactive ion etch (RIE), strip, dielectric barrier etch) and wetcleans (e.g., post RIE dilute hydrofluoric (DHF) cleans). Additionally,penetration of metals used in the liner layer (e.g., Ta, TaN) or theseed layer (e.g., Cu, Ru) into the pores of the dielectric can occurwhen porosity is high and the material is characterized by a high degreeof pore connectivity. This leads to degradation of the dielectric breakdown strength and degradation of the leakage characteristics of thedielectric. All of these issues collectively cause reliabilitydegradation in BEOL structures made using highly porous ULK dielectrics.

Various prior art techniques combat the above-identified issues indifferent manners. In one example, there are techniques to partiallyrepair dielectric damage from plasma exposures. See, e.g., Y. S. Mor, T.C. Chang, P. T. Liu, T. M. Tsai, C. W. Chen, S. T. Yan, C. J. Chu, W. F.Wu, F. M. Pan, W. Lur, and S. M. Sze, “Effective repair to ultra-low-kdielectric material (k.apprx.2.0) by hexamethyldisilazane treatment,” J.Vac. Sci. Technol., B, vol. 20, pp. 1334-1338, 2002. In another example,there have been attempts to seal surface-connected pores to preventmetal penetration. See, e.g., R. J. O. M. Hoofman, V. H. Nguyen, V.Arnal, M. Broekaart, L. G. Gosset, W. F. A. Besling, M. Fayolle, and F.Iacopi, “Integration of low-k dielectric films in damascene processes,”in Dielectr. Films Adv. Microelectron., M. Baklanov, K. Maex, and M.Green, Eds. New-York: Wiley, 2007, pp. 199-250. However, thesetechniques require deposition of additional layers which can increasethe effective dielectric constant of the integrated BEOL structure.

BRIEF SUMMARY

In one exemplary embodiment of the invention, a method comprising:providing a structure comprising a first layer overlying a substrate,where the first layer comprises a dielectric material having a pluralityof pores; applying a filling material to an exposed surface of the firstlayer; heating the structure to a first temperature to enable thefilling material to homogeneously fill the plurality of pores; afterfilling the plurality of pores, performing at least one process on thestructure; and after performing the at least one process, removing thefilling material from the plurality of pores by heating the structure toa second temperature to decompose the filling material.

In another exemplary embodiment of the invention, a program storagedevice readable by a machine, tangibly embodying a program ofinstructions executable by the machine for performing operations, saidoperations comprising: providing a structure comprising a first layeroverlying a substrate, where the first layer comprises a dielectricmaterial having a plurality of pores; applying a filling material to anexposed surface of the first layer; heating the structure to a firsttemperature to enable the filling material to homogeneously fill theplurality of pores; after filling the plurality of pores, performing atleast one process on the structure; and after performing the at leastone process, removing the filling material from the plurality of poresby heating the structure to a second temperature to decompose thefilling material.

In a further exemplary embodiment of the invention, a semiconductorstructure comprising: a substrate; and a first layer overlying thesubstrate, where the first layer comprises a dielectric material havinga plurality of pores, where the plurality of pores are homogeneouslyfilled by a filling material.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The foregoing and other aspects of embodiments of this invention aremade more evident in the following Detailed Description, when read inconjunction with the attached Drawing Figures, wherein:

FIG. 1 shows a flowchart illustrating one non-limiting example of amethod for practicing the exemplary embodiments of this invention;

FIGS. 2-13 show a semiconductor wafer at various stages of processing inpracticing the exemplary method depicted in FIG. 1;

FIGS. 14 and 15 show x-ray reflectivity scans for six examplesillustrative of suitable conditions that enable homogeneouspore-filling;

FIGS. 16-18 depict flowcharts illustrating non-limiting examples ofmethods for practicing the exemplary embodiments of this invention; and

FIG. 19 shows examples of free radical initiators.

DETAILED DESCRIPTION

Although the design of a low-k dielectric material with desirableproperties for implementation is demanding enough, the complexity ofmodern semiconductor manufacturing processes adds further complications.Some of these are a direct result from trying to utilize SiO₂-basedprocesses with porous, low-k dielectric materials that are considerablyless forgiving. In this regard, adding porosity may not result inredeeming values (e.g., improved characteristics) other than loweringthe dielectric constant. Critical damage to the low dielectric porousmaterial can occur at different stages of the integration process,including: hard-mask deposition, reactive ion etch, photo-resist strip,liner deposition, chemical mechanical polishing, and cap deposition, asnon-limiting examples. Potential solutions present themselves in theform of pore sealing approaches. To date, two pore sealing techniqueshave been explored. The first interposes an additional layer between theILD and the barrier layer. The deposition can be accomplished bychemical vapor deposition (CVD) or spin-on techniques, as non-limitingexamples, and the material can be organic or inorganic in nature. Theinherent k-value of this material will have a direct effect on theoverall dielectric constant and for this reason materials withrelatively low dielectric constants are preferred. Many differentmaterials have been reported, ranging from SiO₂ to organic polymers. Thedrawback of this approach lies in the introduction of new interfaceswhich may impact adhesion. In addition, the additional layer at the viabottom could adversely affect the cap-open step and result in damage tothe line bottom.

Alternatively, pore sealing can be effected by plasma exposure so as toselectively damage and densify the outer few nanometers of the via/linesidewalls. By fine-tuning and careful selection of plasma chemistries,it is possible to control densification and plasma damage.Unfortunately, this approach works best for microporous materials, whilemesoporous materials are easily damaged deep into the ILD (due tointerconnectivity) with limited pore sealing success.

Another approach addresses the pore sealing problem from a differentperspective. These are so-called “solids first” or “porosity last”alternative integration schemes typically using templating porogens(see, e.g., U.S. Pat. No. 6,451,712). These integration schemes can befurther subdivided into post-etch burnout (PEBO) or post-chemicalmechanical polishing (CMP) burnout (PCBO) of the porogen. PEBO requiressidewall densification, possibly through porogen decomposition duringetch, to subsequently facilitate uniform deposition of liner and metal.PCBO can only be implemented with a top hardmask that is permeable tothe porogen decomposition products or by polishing off the top hardmaskfully in the CMP step. However, due to temperature limitations dictatedby the porogen, process temperatures during damascene processing arelimited to below the decomposition temperature of the porogen. Inaddition, ILD shrinkage during the final porogen burnout is preferablyless than 1% in order to maintain integrity of the interconnectstructures. Such a target value may be difficult to achieve.

Thus, pore sealing is a difficult process and becomes more difficult aspore diameter increases into the supermicroporous and mesoporous range(>1.5-2 nm), as is typically the case to achieve a dielectric constantk≦2.4. In this size regime, to date PEBO and PCBO schemes appear to bethe only hope. However, the requirements associated with thesestrategies (e.g., shrinkage, special permeable caps) make theseapproaches challenging to implement with current integration processes.Plasma sealing currently appears to be the preferred route. Thistechnique requires that the pore size remain in the microporous regimewith a pore size below 1.5 nm, even at high porosities, which isdifficult to achieve.

One prior art technique, as disclosed by U.S. Pat. No. 6,703,324,introduces a secondary component into the void fraction of a porousmedium (low dielectric constant film) in order to temporarily improvethe mechanical properties such that the porous film has mechanicalcharacteristics of a much stiffer film. Once a process operation such asa chemical mechanical polishing process, which requires greatermechanical strength than that provided by the porous film alone, iscompleted, the secondary component is removed by displacement ordissolution.

Another prior art technique, as disclosed by U.S. Pat. No. 7,303,989,impregnates the pores of a zeolite low-k dielectric layer with a polymerand forms an interconnect structure therein. This mechanicallystrengthens the dielectric layer and prevents metal deposits within thepores.

Below, and with reference to FIGS. 1-13, is described one, non-limitingexemplary embodiment illustrating how filling the pores of a porousdielectric film (e.g., a low-k or ULK dielectric film) may be beneficialfor processing carried out on the wafer. FIG. 1 depicts a flowchartillustrating one non-limiting example of such a method and is furtherreferred to below with reference to FIGS. 2-13. It is noted that thedescribed exemplary method is for forming a single-damasceneinterconnect structure. In other exemplary embodiments, a differentstructure may be formed and/or utilized.

In FIG. 2 (step 101 of FIG. 1), a semiconductor wafer 200 that has aprevious interconnect layer 212 deposited on top is first coated with anILD layer 210 of a porous material containing empty pores (e.g., anorganosilicate), for example, deposited by the best known techniques. Asan example, the ILD layer 210 may be suitably formed of single or dualdamascene wiring with a high electrical conductivity material (e.g.,copper, aluminum, alloys thereof) embedded in a suitable ILD (porous ornonporous) and optionally capped with a diffusion barrier dielectric(e.g., SiN, NBLOK). Detailed make up of layer 212 is omitted in FIGS.2-12 for purposes of clarity.

In FIG. 3 (step 102 of FIG. 1), the pores of the porous dielectric arehomogeneously refilled with a filling material (e.g., an organic polymer214). There is an excess layer of the organic polymer 214 that forms atthe surface of the filled ILD film 230.

In FIG. 4 (step 103 of FIG. 1), the excess of organic polymer 214 thatwas deposited on top of the filled ILD film 230 is then removed by asuitable method, such as plasma etch, RIE strip, wet dissolution orgentle polishing. Care should be exercised not to remove the polymerfrom the filled pores in the structure.

In FIG. 5 (step 104 of FIG. 1), a hardmask layer 216 is deposited on topof the filled ILD layer 230, for example, using plasma enhanced chemicalvapor deposition (PECVD) or spin-on techniques. The hardmask 216 can beformed of a suitable material including, as non-limiting examples, SiO₂,Al₂O₃, SiN, Si₃N₄, SiC, SiCOH or another suitable hardmask material asknown in the art. The hardmask layer 216 may further be formed by morethan one layer of material, though the total thickness preferably shouldbe less than 250 nm and, more preferably, less than 100 nm.

In FIG. 6 (step 105 of FIG. 1), a photoresist layer 218 is applied tothe top of the hardmask layer 216, exposed to generate a desiredpattern, developed and then baked (e.g., at a temperature on the orderof 200° C. or less).

In FIG. 7 (step 106 of FIG. 1), the hardmask layer 216 and the filledILD layer 230 are etched (e.g., in a plasma etching process) to removethem in those regions defined by openings in the photoresist pattern 218on top of the hardmask layer 216, creating the opening 220.

In FIG. 8 (step 107 of FIG. 1), any remnants of the resist layer 214 areremoved by a strip process. It should be noted that this is the stepwhere the porosity of the organosilicate is exposed to the strip processchemistry used to remove the photo-resist and damage would otherwiseoccur to the pores of the filled ILD layer 230 if they were not filledwith the polymer. Without first filling the pores, after such anexposure the dielectric constant and the leakage current of the ILDincrease significantly. In contrast, as the ILD is in a nonporous hybridstate enriched in carbon due to the refill material now present in theoriginal pores, little or no damage occurs to the filled ILD layer 230.

In FIG. 9 (step 108 of FIG. 1), a liner material is deposited to form aliner layer 222 on top of the hardmask layer 216. The liner layer 222may be comprised of a material such as TaN, TiN, Ti, Ta, or variouscombinations thereof, as non-limiting examples, for achieving adhesionand diffusion barrier properties.

At this stage, in some exemplary embodiments a seed layer (e.g., copper)is deposited on top of the liner layer 222 (not shown). The seed layermay be deposited by sputtering, for example, and may be used tofacilitate subsequent electroplating.

In FIG. 10 (step 109 of FIG. 1), the etched opening 220 is filled with ametal 224, such as copper, for example. The metal may be formed byelectroplating, for example, and overfills the opening 220.

In FIG. 11 (step 110 of FIG. 1), after the etched opening 220 is filledwith the metal 224, the electronic structure 200 is planarized (e.g., bya chemical mechanical polishing (CMP) process) to achieve a planarsurface with a metal inlaid structure. In this CMP step, polishing isperformed until all of the excess metal, liner and hardmask on top ofthe filled ILD layer 230 are removed, thus exposing at least a topsurface of the filled ILD layer 230.

In FIG. 12 (step 111 of FIG. 1), the filling material (e.g., the organicpolymer) is removed from the pores, for example, by decomposing it usinga thermal curing or a thermal curing assisted by ultraviolet (UV)irradiation, as non-limiting examples.

In FIG. 13 (step 112 of FIG. 1), a cap layer 226 of an insulatingmaterial (e.g., silicon carbide, silicon nitride, silicon carbonitride,combinations thereof) is deposited on top in order to prevent diffusionof the metal and to protect the electronic device 200 (e.g., frommechanical abrasion or other damage).

As described above, by filling the pores of the porous ILD (e.g., with apolymer, an organosilicate) damage to the ILD (e.g., to the pores of theILD) can be avoided during processing of the structure. Also as notedabove, much of the potential for damage stems from the strip processchemistry used to remove the photo-resist. Without filling the pores,the dielectric constant and the leakage current of the ILD may beadversely affected (e.g., significantly increased).

Filling of the pores is not a simple task. First, the temperature mustbe controlled. That is, in order to achieve any amount of pore-fillingthe temperature must be raised to enable the material (e.g., a polymer)to penetrate into the porous material. By the same turn, the temperaturemust remain below the decomposition temperature of the filling material.Second, achieving homogeneous filling of the porous material is evenmore difficult. Unless the proper conditions are utilized, thepore-filling will not be homogeneous.

Inhomogeneous filling of the porous material is very undesirable becauseit yields a material having regions with different properties throughoutits thickness. These variations would cause severe issues, such as:differences in etch rate leading to uncontrolled etch depth and profile,and differences in resistance to plasma exposure affecting theelectrical integrity of the film. Such variations are likely to haveadverse effects on the properties and/or operation of the finalstructure.

It is noted that the references herein to “homogeneous” filling of thepores with a material refer to a substantially thorough, complete anduniform filling of the pores. That is, homogeneous filling will resultin the filled porous material being substantially uniform in compositionand, thus, properties. Accordingly, “inhomogeneous” filling results inthe filled porous material being non-uniform in composition andproperties.

In accordance with the above, exemplary embodiments of the inventionenable homogeneous filling of the porous material to provide an improvedstructure. As an example, homogeneous filling may be realized byutilizing appropriate conditions and/or characteristics, such as atemperature in the appropriate range based at least on the fillingmaterial (e.g., polymer) and the pore size, for example. Generally, withthe same filling material a smaller pore size will need a highertemperature (i.e., greater energy to push the filling material into thesmaller pores). It should further be noted that the conditions forhomogeneous filling are dependent on the type or composition of theporous material.

Various examples are described immediately below. These examples arefurther illustrative of suitable conditions that enable homogeneouspore-filling and, for example, show that a narrow range of temperaturesenable homogeneous pore-filling at least for pore sizes from about 1.5-8nm. FIGS. 14 and 15 show x-ray reflectivity scans of intensity (counts)as a function of incident angle (ω, degrees). It should be noted thatthe symbols (triangle, square) in FIGS. 14 and 15 are not data points inand of themselves and are merely indicia provided to distinguish amongthe lines of the graphs.

The following examples use a solution of 5 wt. % poly(methylmethacrylate) (weight average molecular weight (Mw)=4700 g/mol) in PGMEA(referred to as “Poly-1”) and a solution of 15 wt. % poly(ethyleneglycol) (Mw=18500 g/mol) in water (referred to as “Poly-2”). Materialdetails for the low-k materials, POCS-1 and POCS-2, are provided inTable 1 below. POCS-1 and POCS-2 are names used here to identify twoporous films having different properties. To prepare these referenceporous films, a microelectronic grade formulation composed of athermally stable organosilicate oxycarbosilane polymer (OCS) and athermally decomposable organic polymer was used. The ratio of theorganic to the organosilicate oxycarbosilane was such that films wherethe organic polymer has been decomposed reproducibly have a porosity of36% and 45.5%, respectively, as measured by both nitrogen adsorption(BJH-KJS method) and ellipsometric porosimetry using toluene as theadsorbent (Kelvin model). The density and thickness were obtained usingX-ray reflectivity and the refractive index using spectro-reflectometry.POCS-1 and POCS-2 were synthesized by spin-coating the above formulationon an 8-inch silicon wafer, applying first a post-applied bake on a hotplate at 85° C. for 2 minutes and then curing the film in a YieldEngineering Systems Inc. (YES®) polyimide bake oven at 250° C. for 15minutes using a 5° C./min ramp. The film was then cured at 400° C. for 7minutes under UV irradiation. This last step leads to the densificationof the organosilicate network and the complete removal of the porogen.These two materials were selected to demonstrate that refilling ispossible for materials having a pore size between about 1.5 and at least8 nm

TABLE 1 Pore size Density Thickness Refractive diameter g/cm³ nm indexPorosity nm POCS-1 0.986 520 1.304 33% 1.5-3 POCS-2 0.753 560 1.250 46%  6-8

EXAMPLE 1

Poly-1 was spin-coated on top of POCS-1 at 1500 rpm for 1 minute andleft at room temperature (20-25° C.). The excess polymer (polymeroverburden) was removed. POCS-1 was then analyzed by X-ray reflectivity(XRR). The XRR scan is presented in FIG. 14, and indicates that norefill of the porosity by the polymer was observed. It indicates that norefill of the porosity by the polymer is obtained because the criticalangle corresponds to the critical angle of the pristine material. Thisconfirms that the film density did not change and, consequently, thatthe pores are still empty.

EXAMPLE 2

Poly-1 was spin-coated on top of POCS-1 at 1500 rpm for 1 minute andheated at 175° C. for 1 minute. The excess polymer (polymer overburden)was removed. POCS-1 was then analyzed by XRR. The XRR scan is presentedin FIG. 14, and indicates that an inhomogeneous refill of the porosityby the polymer was observed. It is first observed that the criticalangle has shifted from ˜0.145° to ˜0.168°. This shift indicates that thefilm density has changed and, therefore, the pores are at leastpartially filled with the polymer. Nevertheless, some substructures areobserved in the critical angle, suggesting that the density is notidentical throughout the whole film thickness. Indeed, after fitting thedata with a multilayer stack, it was found that an inhomogeneous refillof the porosity by the polymer was observed. The pores closer to thesurface of the film are more refilled than the pores at the bottom ofthe film. If a subsequent thermal cure at 400° C. for at least 15minutes is performed, the polymer inside the pores is fully decomposedand the XRR scan of example 1 will be obtained.

EXAMPLE 3

Poly-1 was spin-coated on top of POCS-1 at 1500 rpm for 1 minute andheated at 250° C. for 1 minute. The excess polymer (polymer overburden)was removed. POCS-1 was then analyzed by XRR. The XRR scan is presentedin FIG. 14, and indicates that a homogeneous refill of the porosity bythe polymer was observed. It is first observed that the critical anglehas shifted from ˜0.145° to ˜0.170°. This shift indicates that the filmdensity has changed and, therefore, the pores are at least partiallyfilled with the polymer. In addition, no substructures were detected inthe critical angle, suggesting that the density is identical throughoutthe whole film thickness. Indeed, the experimental data can be fittedwith a monolayer system indicating that a homogeneous refill of theporosity by the polymer was obtained. If a subsequent thermal cure at400° C. for at least 15 minutes is performed, the polymer inside thepores is fully decomposed and the XRR scan of example 1 will beobtained.

EXAMPLE 4

Poly-2 was spin-coated on top of POCS-2 at 1500 rpm for 1 minute andleft at room temperature (20-25° C.). The excess polymer (polymeroverburden) was removed. POCS-2 was then analyzed by XRR. The XRR scanis presented in FIG. 15, and indicates that no refill of the porosity bythe polymer was observed because the critical angle corresponds to thecritical angle of the pristine material. This confirms that the filmdensity has not changed and, consequently, that the pores are stillempty.

EXAMPLE 5

Poly-2 was spin-coated on top of POCS-2 at 1500 rpm for 1 minute andheated at 150° C. for 1 minute. The excess polymer (polymer overburden)was removed. POCS-2 was then analyzed by XRR. The XRR scan is presentedin FIG. 15, and indicates that an inhomogeneous refill of the porosityby the polymer was observed. It is first observed that the criticalangle has shifted from ˜0.13° to ˜0.14°. This shift indicates that thefilm density has changed and, therefore, the pores are at leastpartially filled with the polymer. Nevertheless, some substructures areobserved in the critical angle, suggesting that the density is notidentical throughout the whole film thickness. Indeed, after fitting thedata with a multilayer stack, an inhomogeneous refill of the porosity bythe polymer was observed. The pores closer to the surface of the filmare more refilled than the pores at the bottom of the film. If asubsequent thermal cure at 400° C. for at least 15 minutes is performed,the polymer inside the pores is fully decomposed and the XRR scan ofexample 4 will be obtained.

EXAMPLE 6

Poly-2 was spin-coated on top of POCS-2 at 1500 rpm for 1 minute andheated at 300° C. for 1 minute. The excess polymer (polymer overburden)was removed. POCS-2 was then analyzed by XRR. The XRR scan is presentedin FIG. 15, and indicates that a homogeneous refill of the porosity bythe polymer was observed. It is first observed that the critical anglehas shifted from ˜0.13° to ˜0.165°. This shift indicates that the filmdensity has changed and, therefore, the pores are at least partiallyfilled with the polymer. In addition, no substructures were detected inthe critical angle, suggesting that the density is identical throughoutthe whole film thickness. Indeed, the experimental data can be fittedwith a monolayer system, indicating that a homogeneous refill of theporosity by the polymer was obtained. If a subsequent thermal cure at400° C. for at least 15 minutes is performed, the polymer inside thepores is fully decomposed and the XRR scan of example 4 will beobtained.

In view of the above examples, the following two conclusions are noted:

-   (1) Filling POCS-1 (pore diameter of about 1.5-3 nm) with    poly(methyl methacrylate) (Mw=4700 g/mol) needs a temperature    greater than 175° C. for homogeneous filling of the pores; and-   (2) Filling PCS-2 (pore diameter of about 6-8 nm) with poly(ethylene    glycol) (Mw=18500 g/mol) needs a temperature greater than 150° C.    for homogeneous filling of the pores.

Various exemplary embodiments of the invention relate to methods andtechniques for fabrication of semiconductor structures (e.g.,interconnect structures) that can be employed in a microelectronicdevice, such as: high speed microprocessors, application specificintegrated circuits (ASICs), and memory devices, as non-limitingexamples. As a non-limiting example, the exemplary interconnectstructures may comprise at least one conductive feature, formed on asubstrate, with the substrate further comprising at least one insulatinglayer surrounding the at least one conductive feature. For example, theat least one insulating layer may surround the at least one conductivefeature at its bottom and lateral surfaces. The exemplary structurefurther may comprise at least one conductive barrier layer disposed forat least one interface between the at least one insulating layer and theat least one conductive feature. In some exemplary embodiments, thecombination of the at least one conductive feature and the at least oneinsulating layer may be repeated to form a multilevel interconnectstack. The exemplary interconnect structure may comprise a silicon wafercontaining microelectronic devices, a ceramic chip carrier, an organicchip carrier, a glass substrate, a GaAs, SiC or other semiconductorwafer, a circuit board or a plastic substrate, as non-limiting examples.

In accordance with the exemplary embodiments of the invention, a methodfor forming a porous dielectric material layer in an electronicstructure and the structure formed are disclosed.

It is therefore one object of the exemplary embodiments of the inventionto provide a method for forming a porous dielectric material layer in anelectronic structure that does not have the drawbacks or shortcomings ofthe conventional methods associated with processing and integrationinduced damage to the porous dielectric materials.

In one exemplary embodiment, a method for forming a porous dielectricmaterial layer in an electronic structure is carried out by the steps ofproviding a pre-processed electronic substrate, depositing a layer ofporous dielectric material on top of the pre-processed electronicsubstrate, refilling the pores of the porous dielectric material with apolymeric species, defining and patterning the layer of dielectricmaterial using a photo-resist and hard-mask, removing the photo-resist,depositing the liner, filling the structure with copper, polishing theexcess of copper and the residual hard-mask and thermally curing theelectronic substrate to decompose the polymer in the pores (e.g.,temperatures typically about 350° C. to about 425° C.) transforming thepores-filled dielectric material into a porous dielectric material.

In another exemplary embodiment, a method for forming a porousdielectric material layer in an electronic structure can be carried outby the steps of providing a pre-processed electronic substrate,depositing a layer of porous dielectric material on top of thepre-process electronic substrate, refilling the pores of the porousdielectric material with a polymeric species, defining and patterningthe layer of dielectric material, removing the photo-resist, depositingthe liner, filling the structure with copper, polishing the excess ofcopper and the residual hard-mask and decomposing the polymer in thepores by using thermal curing assisted with UV irradiation (e.g.,temperatures typically about 100° C. to about 400° C.) transforming thepores-filled dielectric material into a porous dielectric material.

It is another object of the exemplary embodiments of the invention toprovide a method for forming a porous dielectric material layer in anelectronic structure that is not subjected to attack by reactive ionetching gases during a patterning process. It is another object of theexemplary embodiments of the invention to provide a method for forming aporous dielectric material layer in an electronic structure that is notsubjected to attack by photo-resist strip during a patterning process.It is another object of the exemplary embodiments of the invention toprovide a method for forming a porous dielectric material layer in anelectronic structure that is not subjected to liner penetration duringthe liner deposition process. It is another object of the exemplaryembodiments of the invention to provide a method for forming a porousdielectric material layer in an electronic structure that is notsubjected to attack by CMP slurry during chemical metal polishing. It isanother object of the exemplary embodiments of the invention to providea method for forming a porous dielectric material layer in an electronicstructure that mitigates line bottom roughening, pitting andmicro-trenching during cap opening process.

A further exemplary embodiment of the invention provides a method forforming a porous dielectric material layer in an electronic structure byfirst forming a porous dielectric material layer that has reached itsmaximum shrinkage, refilling the pores with a monomer and a photoinitiator, exposing the material to UV to create a polymer inside thepores, patterning the layer in a reactive ion etching process, removingthe photo-resist, depositing the liner, filling the structure withmetallic copper, removing the excess of copper and hard-mask usingchemical metal polishing and then forming pores in the dielectricmaterial layer by removing the filling material.

A further exemplary embodiment of the invention provides a method forforming a porous dielectric material layer in an electronic structure byfirst forming a porous dielectric material layer that has reached itsmaximum shrinkage, refilling the pores with a monomer and a radicalinitiator, thermally curing the material to create a polymer inside thepores, patterning the layer in a reactive ion etching process, removingthe photo-resist, depositing the liner, filling the structure withmetallic copper, removing the excess of copper and hard-mask usingchemical metal polishing and then forming pores in the dielectricmaterial layer by removing the filling material.

Another exemplary embodiment of the invention provides an electronicstructure that has a layer of porous dielectric material formed thereinwherein the layer of porous material has a porosity between about 25vol. % and about 80 vol. %. Another exemplary embodiment of theinvention provides an electronic structure that has a layer of porousdielectric material formed therein for electrical insulation wherein theporous dielectric material has a dielectric constant between about 1 andabout 2.4, preferably between 1.4 and 2.4. Another exemplary embodimentof the invention provides an electronic structure that has a layer ofporous dielectric material formed therein for electrical insulationwherein the conductive metal may be copper, aluminum, or another metalsuch as silver, gold and alloys thereof, as non-limiting examples.Another exemplary embodiment of the invention provides an electronicstructure that has a layer of porous dielectric material formed thereinfor electrical insulation wherein the dielectric material is depositedby PECVD or spin-on techniques.

Another exemplary embodiment of the invention provides an electronicstructure that has a layer of porous dielectric material formed thereinfor electrical insulation, wherein the dielectric material comprises atleast one of methyl silsesquioxane (MSSQ), hydrogen silsesquioxane(HSQ), oxycarbosilane (OCS), silica, copolymers thereof and aromaticthermoset polymers such as the SILK® Semiconductor Dielectric or Flare®,as non-limiting examples. Non-limiting examples of suitable porousdielectric materials include those mentioned in the following U.S. Pat.Nos. 7,479,306, 7,312,524, 7,288,292, 7,282,458, and 7,229,934. Furthernon-limiting examples of suitable porous dielectric materials includethose mentioned in U.S. Patent Application Publication Number2008/0009141.

Another exemplary embodiment of the invention provides an electronicstructure that has a layer of porous dielectric material formed thereinfor electrical insulation wherein the dielectric material can berefilled with polymers which are already well known in the art. In oneexemplary embodiment, the decomposable polymer is a linear or branchedpolymer selected from the group of polyimides, polyamic acid, poly(amicalkyl esters), polybenzoxazoles, polyarylene ethers, polyarylenes,parylenes, polynaphtalenes, silicon-substituted polyimides,polyquinoxalines, poly(2-alkyl oxazolines),poly(N,N-dialkylacrylamides), poly(caprolactones), polyesters,polylactides, polystyrenes, substituted polystyrenes, poly-alphamethylstyrene, substituted poly-alpha methyl polystyrenes, aliphaticpolyolefins, polynorbornenes, polyacrylates, polymethacrylates, andpolyethers. Among the latter, particularly polyethylene oxide,polypropylene oxide and polytetrahydrofuran are preferred. Thedecomposable polymer is preferably a linear polymer, a linear di ortri-block copolymer, hyperbranched or a polymeric unimolecularamphiphile. Reference is made to U.S. Pat. Nos. 5,895,263 and 6,399,666for further examples of suitable decomposable polymers.

Another exemplary embodiment of the invention provides a method forforming an interlayer dielectric material (ILD) layer suitable for usein an electronic structure, and more particularly, discloses a methodfor forming a porous dielectric material layer in an electronicstructure by first forming a first porous dielectric material layer thathas reached its maximum shrinkage, and then refilling the pores with athermally labile material thus rendering the ILD nonporous, patterningthe nonporous ILD layer in a reactive ion etching process, removing thephoto-resist, depositing the liner and seed metals, filling thestructure with conductive metal such as copper, removing the excess ofall metals and hard-mask from above the ILD using chemical mechanicalpolishing and then re-forming pores to form a second and finaldielectric material layer trough a thermal or thermal/UV curing processto remove the filling material.

Another exemplary embodiment of the invention provides a method forforming a porous dielectric material layer in an electronic structure byfirst providing an electronic structure that has devices built on top,depositing a layer of a porous dielectric material layer that hasreached its maximum shrinkage on top of the electronic structure, andthen refilling the pores with a thermally labile material, patterningthe layer in a reactive ion etching process, removing the photo-resist,depositing the liner, filling the structure with metallic copper,removing the excess of copper and hard-mask using chemical mechanicalpolishing and then annealing the electronic structure at a temperaturenot less than the volatilization temperature of the thermally labilematerial to generate the porous dielectric material.

In some exemplary embodiments, the filling material comprises an organicthermally labile material which has a decomposition temperature higherthan the temperatures used during at least one of (and possibly all of):hard-mask deposition, lithography, reactive ion etch, photo-resiststrip, liner deposition, copper seed and plate and CMP. As an example,the organic thermally labile material may have a decompositiontemperature between 300° C. and 425° C. In some exemplary embodiments,maximum homogeneous filling may be obtained by heating the structure forabout or less than 1 minute.

Another exemplary embodiment of the invention provides an electronicstructure that has a layer of damage-free porous dielectric materialformed therein for electrical insulation which includes a pre-processedelectronic substrate, a layer of porous dielectric material that has aporosity between about 25 vol. % and about 80 vol. % formed andpatterned on the pre-processed electronic substrate, and a conductivemetal filling the pattern formed in the layer of porous dielectricmaterial. The porous dielectric material may have a dielectric constantbetween about 1 and about 2.4, and preferably between about 1.4 andabout 2.4. The conductive metal filling the pattern may comprise copper,aluminum, silver or gold forming a single damascene (e.g., comprisingwiring lines only) or a dual damascene (e.g., comprising wiring linesand contact vias) interconnect structure.

Another exemplary embodiment of the invention provides a process whicheliminates the problem of damage to the porous structure during thedielectric material patterning, etching, metal filling and/or CMPprocess steps. One exemplary method patterns a material where the poreshave been refilled with an organic material leading to a non-porousstructure during these processes such that the problem of damage to theporous structure and penetration of metallic or other processingchemical species into pores can be avoided.

In accordance with the exemplary embodiments of the invention,structures can be built with porous low k materials such as silicatematerials (e.g., silica, hydrogensilsesquioxane, methylsilsesquioxane,oxycarbosilane and copolymers thereof), as a non-limiting example. Insome exemplary embodiments, the porosity is interconnected to ensure agood refilling of the pores with the polymeric material. This isgenerally the case for porosity >25%. The problems encountered in theconventional prior art damascene method are solved by taking advantageof the nonporous nature of the pores refilled dielectric material duringprocessing steps, thus preventing any damage to the porous structureduring integration.

In many cases, current low dielectric constant materials considered fork≦2.4 are first deposited with a chemical composition containing asilicate or an organosilicate and various amounts of a second phasepolymeric material, which is a pore-forming agent, referred to as“porogen” in the art. These composite materials are then made into aporous film with a dielectric constant in a range between about 1.4 andabout 2.4 after removing the porogen phase. The word “about” used inthis writing indicates a range of values. For example, such an exemplaryrange may be of +/−10% from the average value given. The second phasepolymeric material, or the pore forming agent, is a material that isusually a long chained organic polymer which can be decomposed andvolatilized and driven from the matrix material, i.e. theorganosilicate, after the film has been cured in a curing process, forexample.

Another exemplary embodiment of the invention provides a method that canbe carried out by first spin-coating a film onto the surface of asilicon wafer and then furnace curing the film at about 400° C. Insteadof a simple thermal cure, the film can also be directly treated in a UVchamber at 350 to 400° C. for 1 to 15 minutes to effect a shorter UVradiation assisted thermal process. The film formed may comprise across-linked organosilicate where the porogen has been fully removed.The film is usually deposited to a thickness, for example, between about50 nm and about 1000 nm, or preferably between about 150 nm and about400 nm, as non-limiting examples. This film has reached its maximumshrinkage if no further treatment at temperatures higher than the curetemperature is performed. A polymer then may be spin-coated onto theporous film and the film is cured on a hot plate at temperatures, forexample, between 100° C. and 250° C., preferably 200 to 250° C., asnon-limiting examples. The polymer is designed such that it infiltratesinto the pores of the cured porous dielectric film below forming anorganic/organosilicate hybrid dielectric film. The excess of polymer ontop the hybrid dielectric film is then removed by using typicalphotoresist strip conditions such as plasma ashing, for example. Ahardmask material is then deposited on top of the hybrid film. Thehardmask material may comprise at least one of SiO₂, Al₂O₃, Si₃N₄, SiCand SiCOH. The hardmask layer deposition should be conducted at atemperature below the decomposition temperature of the organic polymerfilling the pores, preferably at 300° C. or below, as a non-limitingexample. The hardmask may be comprised of more than one layer ofmaterial, however, the total thickness is usually less than 250 nm, forexample, and more preferably less than 100 nm, as a non-limitingexample. The hardmask layer can be deposited by PECVD or spin onmethods, as non-limiting examples. In the case of the PECVD hardmask,the deposition temperature should be lower than the organic polymerdecomposition temperature. In the case of a spin-on hardmask, thesolvent used to spin-coat the hardmask layer should be carefully chosenso as not to remove the organic polymer from the pores of theorganosilicate during spin-coating. The curing temperature of thespin-on hardmask should also be lower than the decomposition temperatureof the organic polymer.

In this exemplary embodiment, a photoresist layer is then applied on topof the hardmask layer and exposed and baked (e.g., at a temperature ofabout 200° C. or less). Next, the hardmask layer is etched in a plasmareactive ion etching process to remove the hardmask and theorganosilicate material in the regions defined by the photoresistpattern. This may be followed by one or more of the usual integrationsteps of photo-resist strip, liner deposition, seed copper depositionand plated copper deposition. The excess of copper, as well as thehardmask layers, is then polished using CMP leaving the interconnectpattern inlaid in the hybrid dielectric layer. Since the hybriddielectric film is a nonporous film made of an organosilicate film withan organic polymer that blocks all the pores, there is no damage to theorganosilicate matrix during all of the different integration stepsdescribed above. Finally, the full structure is heated to a temperaturehigher than the decomposition temperature of the organic polymer (e.g.,400° C. to 425° C.) for a time period long enough to drive out thesecond phase polymeric material from the organosilicate matrix resultingin a porous low-k dielectric film in the finished interconnectstructure. As non-limiting examples, the void content in the finalporous dielectric film may be between about 25 vol. % and about 80 vol.%, or preferably between about 25 vol. % and about 60 vol. %,commensurate with the starting porous organosilicate film beforerefilling. The final curing temperature can also be lower than 400° C.if the thermal removal treatment is assisted by UV irradiation, forexample.

The weight average molecular weight of the organic polymeric materialsused to refill the pores should be below 10,000 g/mol, preferably below5,000 g/mol to enable full penetration into the porous structure.Examples of suitable decomposable polymers have been described above.

In further exemplary embodiments, the polymer is generated in situinside the pores, for example, by using ring opening polymerizationstarting from monomers such as lactones, butyrolactones, valerolactones,caprolactones and lactides, as non-limiting examples. In other exemplaryembodiments, radical initiated polymerization is used starting frommonomers such as acrylates, methacrylates and styrenes, as non-limitingexamples. This exemplary method enables the use of very low molecularweight precursors to be infiltrated into the pores in a facile mannerand converted to a polymer inside the pores by an in situ polymerizationprocess.

Another exemplary embodiment of the invention includes a method forforming a porous dielectric material layer that is used to form a dualdamascene interconnect in a semiconductor structure and is performed byrefilling of the pores after thermal curing of the dual damasceneorganosilicate ILD before hardmask deposition and decomposition of theorganic polymer after direct CMP, similar to the above description for asingle damascene structure.

It is noted that the temperature for the refill may depend, at least inpart, on the nature (composition) of the porous material. For example,if the surface of the porous material has a good affinity for thefilling material (e.g., a polymer), the penetration temperature will belower since less energy is needed to drive the filling material into thepores.

In some exemplary embodiments, the filling material may comprise a lowmolecular weight material. As an example, a low molecular weight may beconsidered to correspond to a molecular weight of the material (e.g., apolymer) between about 100 g/mol and about 5,000 g/mol. Polymers may besynthesized in a wide range of molecular weights and, thus, any suitablepolymer may be utilized in conjunction with the exemplary embodiments ofthe invention. For example, polystyrene may be synthesized with amolecular weight ranging from 100 to 20,000,000 g/mol or more.

In accordance with various exemplary embodiments of the invention, FIG.19 shows examples of suitable (free) radical initiators that may beutilized. One of ordinary skill in the art will appreciate that anysuitable radical initiator may be employed.

Below are further descriptions of various non-limiting, exemplaryembodiments of the invention. The below-described exemplary embodimentsare numbered separately for clarity purposes. This numbering should notbe construed as entirely separating the various exemplary embodimentssince aspects of one or more exemplary embodiments may be practiced inconjunction with one or more other aspects or exemplary embodiments.

(1) In one exemplary embodiment of the invention, and as illustrated inFIG. 16, a method comprising: providing a structure comprising a firstlayer overlying a substrate, where the first layer comprises adielectric material having a plurality of pores (601); applying afilling material to an exposed surface of the first layer (602); heatingthe structure to a first temperature to enable the filling material tohomogeneously fill the plurality of pores (603); after filling theplurality of pores, performing at least one process on the structure(604); and after performing the at least one process, removing thefilling material from the plurality of pores by heating the structure toa second temperature to decompose the filling material (605).

A method as above, where the homogeneous filling of the plurality ofpores comprises a substantially thorough, complete and uniform fillingof the plurality of pores with the filling material. A method as in anyabove, where the homogeneous filling of the plurality of pores resultsin the first layer having a substantially uniform composition. A methodas in any above, where the filling material comprises a polymer or amaterial having a weight average molecular weight below about 10,000g/mol. A method as in any above, where the filling material comprises alow molecular weight material. A method as in any above, where the firsttemperature is dependent on a size of the plurality of pores and acomposition of the filling material. A method as in any above, where thefirst temperature is dependent on a composition of the dielectricmaterial. A method as in any above, where the second temperature isgreater than the first temperature. A method as in any above, where thefirst temperature is dependent on at least one of a composition of thefilling material, a characteristic of the filling material, and acomposition of the dielectric material.

A method as in any above, where the first temperature is dependent on atleast one of a composition of the filling material and a characteristicof the filling material. A method as in any above, where the firsttemperature is selected to ensure homogeneous filling of the pluralityof pores with the filling material. A method as in any above, whereremoving the filling material from the plurality of pores furthercomprises using ultraviolet irradiation. A method as in any above, wherethe filling material comprises a monomer and a photo initiator, themethod further comprising: after filling the plurality of pores andprior to performing the at least one process, exposing the structure toultraviolet radiation to convert the filling material into a polymer. Amethod as in any above, where the dielectric material of the providedfirst layer has reached its maximum shrinkage, where the fillingmaterial comprises a monomer and a radical initiator, where heating thestructure to the first temperature converts the filling material into apolymer. A method as in any above, where heating the structure to afirst temperature to enable the filling material to homogeneously fillthe plurality of pores comprises filling 5% to 100% of the plurality ofthe pores (the porosity) with the filling material (e.g., preferablymore than 60%). A method as in any above, further comprising one or moreaspects of the exemplary embodiments of the invention as describedherein.

A method as in any above, implemented as a computer program. A method asin any above, implemented as a computer program stored (e.g., tangiblyembodied) on a computer-readable medium (e.g., a program storage device,a memory, a computer-readable memory medium, a non-transitory programstorage device). A computer program comprising program instructionsthat, when performed by a processor, perform operations according to oneor more (e.g., any one) of the methods described herein. A method as inany above, implemented as a program of instructions tangibly embodied ona program storage device, execution of the program of instructions by anapparatus (e.g., processor, data processor, machine, computer) resultingin operations comprising the steps of the method.

(2) In another exemplary embodiment of the invention, a program storagedevice readable by a machine, tangibly embodying a program ofinstructions executable by the machine for performing operations, saidoperations comprising: providing a structure comprising a first layeroverlying a substrate, where the first layer comprises a dielectricmaterial having a plurality of pores (601); applying a filling materialto an exposed surface of the first layer (602); heating the structure toa first temperature to enable the filling material to homogeneously fillthe plurality of pores (603); after filling the plurality of pores,performing at least one process on the structure (604); and afterperforming the at least one process, removing the filling material fromthe plurality of pores by heating the structure to a second temperatureto decompose the filling material (605).

A program storage device as in any above, further comprising one or moreaspects of the exemplary embodiments of the invention as describedherein.

(3) In a further exemplary embodiment of the invention, a semiconductorstructure comprising: a substrate; and a first layer overlying thesubstrate, where the first layer comprises a dielectric material havinga plurality of pores, where the plurality of pores are homogeneouslyfilled by a filling material.

A semiconductor structure as in any above, further comprising one ormore aspects of the exemplary embodiments of the invention as describedherein.

(4) In another exemplary embodiment of the invention, an apparatuscomprising: means for providing a structure comprising a first layeroverlying a substrate, where the first layer comprises a dielectricmaterial having a plurality of pores; means for applying a fillingmaterial to an exposed surface of the first layer; means for heating thestructure to a first temperature to enable the filling material tohomogeneously fill the plurality of pores; means for, after filling theplurality of pores, performing at least one process on the structure;and means for, after performing the at least one process, removing thefilling material from the plurality of pores by heating the structure toa second temperature to decompose the filling material.

An apparatus as in any above, further comprising one or more aspects ofthe exemplary embodiments of the invention as described herein.

(5) In a further exemplary embodiment of the invention, and asillustrated in FIG. 17, a method comprising: providing a structurecomprising a first layer overlying a substrate, where the first layercomprises a dielectric material having a plurality of pores (701);applying a filling material to an exposed surface of the first layer,where the filling material comprises a monomer and a photo initiator(702); heating the structure to a first temperature to enable thefilling material to fill the plurality of pores (703); after filling theplurality of pores, exposing the structure to ultraviolet radiation toconvert the filling material into a polymer (704); after exposing thestructure to the ultraviolet radiation, performing at least one processon the structure (705); and after performing the at least one process,removing the polymer from the plurality of pores by heating thestructure to a second temperature to decompose the polymer (706).

A method as above, where the filling of the plurality of pores with thefilling material is homogeneous. A method as in any above, where thefilling of the plurality of pores comprises a substantially thorough,complete and uniform filling of the plurality of pores with the fillingmaterial. A method as in any above, where the filling of the pluralityof pores results in the first layer having a substantially uniformcomposition. A method as in any above, where the filling materialcomprises a material having a weight average molecular weight belowabout 10,000 g/mol. A method as in any above, where the firsttemperature is dependent on a size of the plurality of pores and acomposition of the filling material. A method as in any above, where thefirst temperature is dependent on a composition of the dielectricmaterial. A method as in any above, where the second temperature isgreater than the first temperature. A method as in any above, where thefirst temperature is dependent on at least one of a composition of thefilling material, a characteristic of the filling material, and acomposition of the dielectric material.

A method as in any above, where the first temperature is dependent on atleast one of a composition of the filling material and a characteristicof the filling material. A method as in any above, where the firsttemperature is selected to ensure homogeneous filling of the pluralityof pores with the filling material. A method as in any above, whereremoving the filling material from the plurality of pores furthercomprises using ultraviolet irradiation. A method as in any above,further comprising one or more aspects of the exemplary embodiments ofthe invention as described herein.

A method as in any above, implemented as a computer program. A method asin any above, implemented as a computer program stored (e.g., tangiblyembodied) on a computer-readable medium (e.g., a program storage device,a memory, a computer-readable memory medium, a non-transitory programstorage device). A computer program comprising program instructionsthat, when performed by a processor, perform operations according to oneor more (e.g., any one) of the methods described herein. A method as inany above, implemented as a program of instructions tangibly embodied ona program storage device, execution of the program of instructions by anapparatus (e.g., processor, data processor, machine, computer) resultingin operations comprising the steps of the method.

(6) In another exemplary embodiment of the invention, a program storagedevice readable by a machine, tangibly embodying a program ofinstructions executable by the machine for performing operations, saidoperations comprising: providing a structure comprising a first layeroverlying a substrate, where the first layer comprises a dielectricmaterial having a plurality of pores (701); applying a filling materialto an exposed surface of the first layer, where the filling materialcomprises a monomer and a photo initiator (702); heating the structureto a first temperature to enable the filling material to fill theplurality of pores (703); after filling the plurality of pores, exposingthe structure to ultraviolet radiation to convert the filling materialinto a polymer (704); after exposing the structure to the ultravioletradiation, performing at least one process on the structure (705); andafter performing the at least one process, removing the polymer from theplurality of pores by heating the structure to a second temperature todecompose the polymer (706).

A program storage device as in any above, further comprising one or moreaspects of the exemplary embodiments of the invention as describedherein.

(7) In another exemplary embodiment of the invention, an apparatuscomprising: means for providing a structure comprising a first layeroverlying a substrate, where the first layer comprises a dielectricmaterial having a plurality of pores; means for applying a fillingmaterial to an exposed surface of the first layer, where the fillingmaterial comprises a monomer and a photo initiator; means for heatingthe structure to a first temperature to enable the filling material tofill the plurality of pores; means for, after filling the plurality ofpores, exposing the structure to ultraviolet radiation to convert thefilling material into a polymer; means for, after exposing the structureto the ultraviolet radiation, performing at least one process on thestructure; and means for, after performing the at least one process,removing the polymer from the plurality of pores by heating thestructure to a second temperature to decompose the polymer.

An apparatus as in any above, further comprising one or more aspects ofthe exemplary embodiments of the invention as described herein.

(8) In another exemplary embodiment of the invention, and as illustratedin FIG. 18, a method comprising: providing a structure comprising afirst layer overlying a substrate, where the first layer comprises adielectric material having a plurality of pores, where the dielectricmaterial of the provided first layer has reached its maximum shrinkage(801); applying a filling material to an exposed surface of the firstlayer, where the filling material comprises a monomer and a radicalinitiator (802); heating the structure to a first temperature to enablethe filling material to fill the plurality of pores, where heating thestructure to the first temperature converts the filling material into apolymer (803); after filling the plurality of pores, performing at leastone process on the structure (804); and after performing the at leastone process, removing the polymer from the plurality of pores by heatingthe structure to a second temperature to decompose the polymer (805).

A method as above, where the filling of the plurality of pores with thefilling material is homogeneous. A method as in any above, where thefilling of the plurality of pores comprises a substantially thorough,complete and uniform filling of the plurality of pores with the fillingmaterial. A method as in any above, where the filling of the pluralityof pores results in the first layer having a substantially uniformcomposition. A method as in any above, where the filling materialcomprises a material having a weight average molecular weight belowabout 10,000 g/mol. A method as in any above, where the firsttemperature is dependent on a size of the plurality of pores and acomposition of the filling material. A method as in any above, where thefirst temperature is dependent on a composition of the dielectricmaterial. A method as in any above, where the second temperature isgreater than the first temperature. A method as in any above, where thefirst temperature is dependent on at least one of a composition of thefilling material, a characteristic of the filling material, and acomposition of the dielectric material.

A method as in any above, where the first temperature is dependent on atleast one of a composition of the filling material and a characteristicof the filling material. A method as in any above, where the firsttemperature is selected to ensure homogeneous filling of the pluralityof pores with the filling material. A method as in any above, whereremoving the filling material from the plurality of pores furthercomprises using ultraviolet irradiation. A method as in any above,further comprising one or more aspects of the exemplary embodiments ofthe invention as described herein.

A method as in any above, implemented as a computer program. A method asin any above, implemented as a computer program stored (e.g., tangiblyembodied) on a computer-readable medium (e.g., a program storage device,a memory, a computer-readable memory medium, a non-transitory programstorage device). A computer program comprising program instructionsthat, when performed by a processor, perform operations according to oneor more (e.g., any one) of the methods described herein. A method as inany above, implemented as a program of instructions tangibly embodied ona program storage device, execution of the program of instructions by anapparatus (e.g., processor, data processor, machine, computer) resultingin operations comprising the steps of the method.

(9) In another exemplary embodiment of the invention, a program storagedevice readable by a machine, tangibly embodying a program ofinstructions executable by the machine for performing operations, saidoperations comprising: providing a structure comprising a first layeroverlying a substrate, where the first layer comprises a dielectricmaterial having a plurality of pores, where the dielectric material ofthe provided first layer has reached its maximum shrinkage (801);applying a filling material to an exposed surface of the first layer,where the filling material comprises a monomer and a radical initiator(802); heating the structure to a first temperature to enable thefilling material to fill the plurality of pores, where heating thestructure to the first temperature converts the filling material into apolymer (803); after filling the plurality of pores, performing at leastone process on the structure (804); and after performing the at leastone process, removing the polymer from the plurality of pores by heatingthe structure to a second temperature to decompose the polymer (805).

A program storage device as in any above, further comprising one or moreaspects of the exemplary embodiments of the invention as describedherein.

(10) In another exemplary embodiment of the invention, an apparatuscomprising: means for providing a structure comprising a first layeroverlying a substrate, where the first layer comprises a dielectricmaterial having a plurality of pores, where the dielectric material ofthe provided first layer has reached its maximum shrinkage; means forapplying a filling material to an exposed surface of the first layer,where the filling material comprises a monomer and a radical initiator;means for heating the structure to a first temperature to enable thefilling material to fill the plurality of pores, where heating thestructure to the first temperature converts the filling material into apolymer; means for, after filling the plurality of pores, performing atleast one process on the structure; and means for, after performing theat least one process, removing the polymer from the plurality of poresby heating the structure to a second temperature to decompose thepolymer.

An apparatus as in any above, further comprising one or more aspects ofthe exemplary embodiments of the invention as described herein.

(11) In another exemplary embodiment, a method (e.g., for forming aporous dielectric material layer in an electronic structure) comprises:providing a pre-processed substrate; forming a porous dielectric layer(e.g., comprised of a layer of fully cured porous dielectric material)overlying the substrate; homogeneously refilling the pores of the porousdielectric layer with a filling material (e.g., a polymer, an organicpolymer, in order to render the porous dielectric layer nonporous);performing processing on the structure (e.g., defining and patterninginterconnect pattern openings in the dielectric layer; filling saidinterconnect pattern opening with an electrically conductive material;planarizing the electrically conductive material, for example, bychemical mechanical polishing); subsequently heating the substrate(e.g., the structure) to a temperature high enough to drive out saidfilling material from the pores (e.g., thus transforming the nonporousdielectric material into a porous dielectric material).

A method as in any above, further comprising one or more aspects of theexemplary embodiments of the invention as described herein. A method asin any above, implemented as a computer program. A method as in anyabove, implemented as a computer program stored (e.g., tangiblyembodied) on a computer-readable medium (e.g., a program storage device,a memory, a computer-readable memory medium, a non-transitory programstorage device). A computer program comprising program instructionsthat, when performed by a processor, perform operations according to oneor more (e.g., any one) of the methods described herein. A method as inany above, implemented as a program of instructions tangibly embodied ona program storage device, execution of the program of instructions by anapparatus (e.g., processor, data processor, machine, computer) resultingin operations comprising the steps of the method.

The exemplary embodiments of the invention, as discussed herein and asparticularly described with respect to exemplary methods, may beimplemented in conjunction with a program storage device (e.g., at leastone memory) readable by a machine (e.g., a processor), tangiblyembodying a program of instructions (e.g., a program or computerprogram) executable by the machine for performing operations. Theoperations comprise steps of utilizing the exemplary embodiments orsteps of the method.

The blocks shown in FIGS. 16-18 further may be considered to correspondto one or more functions and/or operations that are performed by one ormore components, circuits, chips, apparatus, processors, computerprograms and/or function blocks. Any and/or all of the above may beimplemented in any practicable solution or arrangement that enablesoperation in accordance with the exemplary embodiments of the inventionas described herein.

In addition, the arrangement of the blocks depicted in FIGS. 16-18should be considered merely exemplary and non-limiting. It should beappreciated that the blocks shown in FIGS. 16-18 may correspond to oneor more functions and/or operations that may be performed in any order(e.g., any suitable, practicable and/or feasible order) and/orconcurrently (e.g., as suitable, practicable and/or feasible) so as toimplement one or more of the exemplary embodiments of the invention. Inaddition, one or more additional functions, operations and/or steps maybe utilized in conjunction with those shown in FIGS. 16-18 so as toimplement one or more further exemplary embodiments of the invention.

That is, the exemplary embodiments of the invention shown in FIGS. 16-18may be utilized, implemented or practiced in conjunction with one ormore further aspects in any combination (e.g., any combination that issuitable, practicable and/or feasible) and are not limited only to thesteps, blocks, operations and/or functions shown in FIGS. 16-18.

The exemplary methods and techniques described herein may be used in thefabrication of integrated circuit chips. The resulting integratedcircuit chips can be distributed by the fabricator in raw wafer form(i.e., as a single wafer that has multiple unpackaged chips), as a baredie, or in a packaged form. In the latter case, the chip is mounted in asingle chip package (e.g., a plastic carrier, with leads that areaffixed to a motherboard or other higher level carrier) or in amultichip package (e.g., a ceramic carrier that has either or bothsurface interconnections or buried interconnections). The chip is thenintegrated with other chips, discrete circuit elements and/or othersignal processing devices as part of either (a) an intermediate product,such as a motherboard, or (b) an end product. The end product can be anyproduct that includes integrated circuit chips, ranging from toys andother low-end applications to advanced computer products having numerouscomponents, such as a display, a keyboard or other input device and/or acentral processor, as non-limiting examples.

The terminology used herein is for the purpose of describing particularexemplary embodiments only and is not intended to be limiting of theexemplary embodiments of the invention. As used herein, the singularforms “a”, “an” and “the” are intended to include the plural forms aswell, unless the context clearly indicates otherwise. It will be furtherunderstood that the terms “comprises” and/or “comprising,” when used inthis specification, specify the presence of stated features, integers,steps, operations, elements and/or components, but do not preclude thepresence or addition of one or more other features, integers, steps,operations, elements, components and/or groups thereof.

Any use of the terms “connected,” “coupled” or variants thereof shouldbe interpreted to indicate any such connection or coupling, direct orindirect, between the identified elements. As a non-limiting example,one or more intermediate elements may be present between the “coupled”elements. The connection or coupling between the identified elements maybe, as non-limiting examples, physical, electrical, magnetic, logical orany suitable combination thereof in accordance with the describedexemplary embodiments. As non-limiting examples, the connection orcoupling may comprise one or more printed electrical connections, wires,cables, mediums or any suitable combination thereof.

Generally, various exemplary embodiments of the invention can beimplemented in different mediums, such as software, hardware, logic,special purpose circuits or any combination thereof. As a non-limitingexample, some aspects may be implemented in software which may be run ona computing device, while other aspects may be implemented in hardware.

The foregoing description has provided by way of exemplary andnon-limiting examples a full and informative description of the bestmethod and apparatus presently contemplated by the inventors forcarrying out the invention. However, various modifications andadaptations may become apparent to those skilled in the relevant arts inview of the foregoing description, when read in conjunction with theaccompanying drawings and the appended claims. However, all such andsimilar modifications will still fall within the scope of the teachingsof the exemplary embodiments of the invention.

Furthermore, some of the features of the preferred embodiments of thisinvention could be used to advantage without the corresponding use ofother features. As such, the foregoing description should be consideredas merely illustrative of the principles of the invention, and not inlimitation thereof.

1. A method comprising: providing a structure comprising a first layeroverlying a substrate, where the first layer comprises a dielectricmaterial having a plurality of pores; applying a filling material to anexposed surface of the first layer; heating the structure to a firsttemperature to enable the filling material to homogeneously fill theplurality of pores; after filling the plurality of pores, performing atleast one process on the structure; and after performing the at leastone process, removing the filling material from the plurality of poresby heating the structure to a second temperature to decompose thefilling material, wherein the homogeneous filling of the plurality ofpores comprises a substantially thorough, complete and uniform fillingof the plurality of pores with the filling material.
 2. The method ofclaim 1, where the homogeneous filling of the plurality of pores resultsin the first layer having a substantially uniform composition.
 3. Themethod of claim 1, where the filling material comprises a polymer or amaterial having a weight average molecular weight below about 10,000g/mol.
 4. The method of claim 1, where the first temperature isdependent on a size of the plurality of pores and a composition of thefilling material.
 5. The method of claim 1, where the first temperatureis dependent on a composition of the dielectric material.
 6. The methodof claim 1, where the second temperature is greater than the firsttemperature.
 7. The method of claim 1, where the first temperature isdependent on at least one of a composition of the filling material and acharacteristic of the filling material.
 8. The method of claim 1, wherethe first temperature is selected to ensure homogeneous filling of theplurality of pores with the filling material.
 9. The method of claim 1,where removing the filling material from the plurality of pores furthercomprises using ultraviolet irradiation.
 10. The method of claim 1,where the filling material comprises a monomer and a photo initiator,the method further comprising: after filling the plurality of pores andprior to performing the at least one process, exposing the structure toultraviolet radiation to convert the filling material into a polymer.11. The method of claim 1, where the dielectric material of the providedfirst layer has reached its maximum shrinkage, where the fillingmaterial comprises a monomer and a radical initiator, where heating thestructure to the first temperature converts the filling material into apolymer.
 12. The method of claim 1, where heating the structure to afirst temperature to enable the filling material to homogeneously fillthe plurality of pores comprises filling 5% to 100% of the plurality ofthe pores with the filling material.
 13. The method of claim 1,implemented as a program of instructions tangibly embodied on a programstorage device, execution of the program of instructions by an apparatusresulting in operations comprising the steps of the method.